Bat-detecting drones could help us find out what the animals get up to when flying. Ultrasonic detectors on drones in the air and on the water are listening in on bats call, in the hope of discovering more about the mammals’ lives beyond the reach of ground-based monitoring devices.
Drone-builder Tom Moore and bat enthusiast Tom August have developed three different drones to listen for bat calls while patrolling a pre-planned route. Since launching the scheme, known as Project Erebus, in 2014, they have experimented with two flying drones and one motorised boat, all equipped with ultrasonic detectors.
The pair’s latest tests have demonstrated the detection capabilities of the two airborne drone models: a quadcopter and a fixed-wing drone. Last month, the quadcopter successfully followed a predetermined course and picked up simulated bat calls produced by an ultrasonic transmitter.
Moore says one of the major hurdles is detecting the call of bats over the noise of the drones’ propellers, which emit loud ultrasonic frequencies. They overcame this with the quadcopter by dangling the detector underneath the body and rotors of the drone.
This is not such a problem for the water-based drone. Last year, Moore and August tested a remote-controlled boat in Oxfordshire, UK, and picked up bat calls thought to belong to common pipistrelle and Daubenton’s bats. The different species often emit different ultrasonic frequencies.
“The amount of noise coming from the boat is almost zero – that turned out to be a really fantastic platform for recording bats on the water,” says August.
Drones like those developed by Moore and August could also be useful for environmental surveys. For example, to determine whether placing wind turbines in a certain area could interfere with bats that are active far above the ground or tree canopy.